#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;
int main()
{
    int a, b, n, ret = 0, sum = 0;
    cin >> a >> b >> n;
    if (n == 0)
    {
        cout << 0;
        return 0;
    }
    int day7 = (a * 5) + (2 * b);
    int preday = n / day7;
    ret += (preday * 7);
    int nextday = n - (preday * day7);
    while (true)
    {
        int workday = 5;
        while (workday--)
        {
            sum += a;
            ret++;
            if (sum > nextday)
            {
                cout << ret;
                return 0;
            }
        }
        int freeday = 2;
        while (freeday--)
        {
            sum += b;
            ret++;
            if (sum > nextday)
            {
                cout << ret;
                return 0;
            }
        }
    }
    return 0;
}